Roller-band devices

ABSTRACT

A roller-band device has a stationary magnetic component and a roller-band cluster with a magnetic component polarized for repulsion by the stationary component. One of the magnetic components may be a permanent magnet while the other is an electromagnetic component. Embodiments show a pair of stationary electromagnets operated to exert counterbiasing forces on a cluster and also a roller element having a coil energized by current supplied through rolling contact with spaced band elements.

United States Patent Harley et al.

[ 51 -Aug. 22, 1972 54]- ROLLER-BAND DEVICES [72] Inventors: Wayne E. Harley, 1315 Richmond Dr., Eau Gallie, Fla. 32935; Ronald D. Coughlin, 100 W. Alma Dr., Melbourne, Fla. 32901 [22] Filed: April 23, 1970 [21] Appl. No.: 31,303

Related U.S. Application Data [63] Continuation-in-partof Ser. No. 767,107, Oct.

[52] U.S. Cl ..335/230, 200/ 153 [51] Int. Cl ..H0lf 7/00 [58] Field of Search ..335/209, 230, 191, 171, 78;

[56] References Cited UNITED STATES PATENTS Wilkes .3 35/209 Wilkes ..200/15 3 OTHER PUBLICATIONS D. F. Wilkes; Rolamite: New Mechanical Design Concept, (SC- RR- 67- 656A); 12/1967; pages 162, 170 & 171.

Primary Examiner-J. D. Miller Assistant lixaminerR. Skudy Attorney-Roger L. Martin [57] ABSTRACT A roller-band device has a stationary magnetic component and a roller-band cluster with amagnetic component polarized for repulsion by the stationary component. One of the magnetic components may be a permanent magnet while the other is an electromagnetic component. Embodiments show a pair of stationary electromagnets operated to exert counterbiasing forces on a cluster and also a roller element having a coil energized by current supplied through rolling contact with spaced band elements.

20 Clains, 12 Drawing Figures 1mm Aug. 22, 1972 3 Sheets-Sheet 2 W 1 4 a M 37 J; WAYNE E.HARLEY RONALD 0. GOUGHLHN MIME/V7025 Patented Aug. 22, 1972 3,686,597

3 Sheets-Sheet 5 FIG. HO

WAYNE E. HARLEY RONALD D. GOUGHLIN ROLLER-BAND DEVICES This application is a continuation-in-part of our application, Ser. No. 767,107, filed Oct. 14, 1968 and entitled Roller-Band'Apparatus."

The invention relates to improvements in roller-band devices of the kind referred to in the following articles to which reference is made. (1) The article entitled The Name Of The Concept Is Rolamite in the Nov. 9, 1967 issue of Machine Design," pages 44 through 48. (2) The article by D. F. Wilkes in the April 1968 issue of Mechanical Engineering" entitled Rolamite Part 1 Nature Of The Device. (3) Research Report SC-RR-67-656A by D. F. Wilkes entitled Rolamite: A New Mechanical Design Concept issued by Sandia Corporation as a prime contractor to the USAEC, and available from Clearinghouse for Federal Scientific and Technical Information, National Bureau of Standards, US. Department of Commerce, Springfield, Virginia, 22151. The basic principles involved in the operation of roller-band devices and various uses for such devices are covered in the above articles and also form the subject matter of US. Pat. Nos.

3,452,175 and 3,452,309 recently issued to the USAEC as assignee of D. F. Wilkes, the inventor.

Roller-band devices of the kind referred to in he aforementioned references include a guideway which has spaced walls and a pair of rotatable members that are located in the space between the walls and entwined in a flexible band member that is maintained under tension in an arrangement that serves to maintain the rotation axes of the rotatable members in parallel. The band has a portion which is disposed between the rotatable members and which partially encompasses the members in a generally S-shaped fashion. The space between the walls of the guideway in these devices is less than the sum of the effective diameters of the rotatable members and under the ten sion appliedto the band member, the rotatable members are urged toward the walls so that the walls serve to support and restrain the members as well as to guide the members during their movement.

The arrangement in the device is such that the rotatable members and the interposed band portion form a cluster that is movable back and forth between the opposite ends of the guideway under the influence of biasing forces that may be applied to the cluster. The advantages attributable to the devices lie principally in the area of minimum friction that arises for reasons of an arrangement that eliminates rolling friction and their adaptation for microminiaturization and use in compact arrangement for condition sensing and other applications.

Roller-band devices of the type contemplated generally fall into two categories. In the first category the cluster may be considered as free rolling in the absence of externally applied biasing forces and structurally, devices in this category have at least a pair of right cylindrical rotatable members which are held in place between parallel walls of the guideway by a flexible band that exerts no biasing-force on the members throughout the range of free rolling movement of the cluster in the guideway.

In the second category, the structures are modified to provide what may be considered as a built-in bias in that they include structural modifications or auxiliary devices that tend to urge the cluster into one or more null or reference positions in its range of movement in the guideway and at which the static biasing forces provided by the structure and/or auxiliary device tends to retain the cluster in a predetermined position. The built-in biasing means advocated can, in turn, be classified into primary and secondary biasing means. In the primary biasing means category fall those modifications in the bands, the rollers and/or in the guideway walls that bias the cluster into a null position. For example, it is known to provide bands with variable widths, with preformed bends and with various types of apertures, as well as to construct the bands out of different materials with the object, in one way or another, of mechanically biasing the cluster into some null position in the guideway and from which the cluster can only be moved for reasons of some other applied biasing force. In the primary category of builtin biasing means there is also the various roller designs that serve to establish a null position for the cluster in its range of movement. For example, the rollers may be provided with surface recesses or may be constructed with materials that provide an eccentric weight distribution that causes'the cluster to assume a null position in fluenced by the eccentric weight distribution. In addition to the above, it is also known to provide misaligned guideway walls and wall recesses as a means for biasing the cluster into a null position at which the static forces applied to the cluster tend to retain the cluster in he position.

As for the secondary category of built-in biasing means used in such devices, the means utilized are primarily in the nature of attachments. For example, in this category it has been proposed to bias the cluster toward one end of the guideway by means of springs or other esilient members that are attached at one end to one of the rollers while the other end is secured to some structure that is stationary with respect to the cluster movement. It has also been advocated to interconnect the rollers with springs or other resilient means at points that are offset from the roller axes as a further means for biasing the cluster into one or more null positions. In addition to springs, it has been advocated to urge the cluster into a null position by means of weights or other static forces that are transmitted to the rollers by pulley arrangements. Those familiar with rollerband devices will be aware that the built-in means used to bias the cluster in any one device may take the form of any one or more of the primary and/or secondary means in a cooperating arrangement that establishes a null position for the cluster for reasons of the sum of the biasing forces applied by the various means.

In theory, if the roller-band cluster is free rolling or if the built-in biasing forces applied to the cluster are uniform throughout the range of movement of the cluster, the distance the cluster moves from a predetermined position in a time unit for reasons of the application to the cluster of a force determined by conditions exterior of the device can be equated to the exterior condition. Because of this, the devices have been advocated as useful for accelerometer and G-switch applications. If the built-in biasing force varies as the cluster is moved from a predetermined null position under the influence of a counterbiasing force, the distance the cluster moves from the null position before attaining a state of equilibrium under the influence of the counterbiasing and built-in biasing forces can be equated to-the counterbiasing force.

Insofar as the inventors are aware the only means which have been suggested for applying counterbiasing forces to the cluster other than by means involving fluid, gravitation and/or inertia considerations are means that involve the use of devices that magnetically attract a component of the roller-band cluster or are applied to the cluster by mechanical means such as pulley attachments to the rollers. The use of magnetic attraction means and pulleys of course, leaves much to be desired and to date, the inventors are unaware of any suggestion that magnetic repulsion means may be used for the application of counterbiasing forces for the cluster.

A general object of the invention is to provide improved roller-band devices. One particular object is to provide improved means for establishing a referenced position for a cluster and for applying counterbiasing forces in response to varying external conditions so that the position of the cluster can be sensed and by reference to the established reference or null position equated to the magnitude of the varying external condition. Another object of the invention is to provide improved electrical responsive means for controlling the movement and position of the roller-band cluster along the guideway. Yet another object is to provide improvements that make it practical to use roller-band devices in metering and continuous control applications in industry. Yet another object is to provide improved means for continuously varying the position of the cluster within its range of movement and in response to varying conditions external of the rollerband device.

In principle, the invention is founded on providing the cluster with a magnetically polarized means that cooperates with another magnetically polarized means which is fixed in location with respect to the cluster but which is polarized in a manner such as to repel the cluster during use of the roller-band device. Either one of the polarized means may be a permanently. magnetized member but the other polarized means is an electromagnetic means that responds to varying current conditions that may be controlled externally of the device and is capable of varying the repelling forces on the cluster in response to such current conditions. In accord with certain aspects of the invention both of the magnetically polarized means may take the form of electromagnetic means that are electrically responsive to current variations and in accord with other aspects of the invention a novel means for providing the cluster with electromagnetic means is provided.

The novel features which are believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention, itself, however,

both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a cross section in elevation through a rollerband device embodying certain aspects of the invention as seen along the lines 1-1 of FIG. 2;

FIG. 2 is a horizontal section taken generally along the lines 2-2 of FIG. 1;

FIG. 2a is a plan view of the band used in the device seen in FIGS. 1 and 2;

FIG. 3 diagrammatically illustrates use of the device seen in FIG. 1 and 2 in a control system for regulating the discharge pressure in a fluid pumping system;

FIG. 4 is a perspective view of another roller-band device embodying the principles of the invention;

FIG. 5 is a side elevational view of the roller-band device shown in FIG. 4;

FIG. 6 is an elevational view taken generally along the lines 6-6 of FIG. 5;

FIG. 7 is a transverse cross sectional view through one of the rotatable members seen in FIG. 4, the view being taken generally along the lines 7--7 of FIG. 8;

FIG. 8 is a longitudinal sectional view along the rotation axis of the rotatable member as'seen along the lines 8-8 of FIG. 7;

FIG. 9 is a side elevational view of another rollerband device embodying certain principles of the inven tion as seen along the lines 99 of FIG. 10;

FIG. 10 is a horizontal sectional view taken along the lines 10l0 of FIG. 9;

and FIG. 11 diagrammatically illustrates use of the device seen in FIGS. 9 and 10 for regulating the volume flow rate in response to changing temperature conditions.

Reference is now made to the embodiment shown and illustrated in FIGS. 1 through 3 inclusive. The roller-band device 10 in this instance includes a guideway 11 with opposite walls 12 and 13 that are equally spaced apart throughout the range of movement of the cluster 14 between the opposite ends 15 and 16 of the guideway 11. The rotatable members 17 and 18 are shown in the form of right cylindrical rollers having diameters .which in summation exceed the distance between the walls 12 and 13 of guideway 11. The flexible band 19 in this instance has a configuration shown in FIG. 2a and by suitable fasteners 20 is secured under tension to diagonally opposite ends of the walls 12 and 13 in an arrangement so that a portion 21 of the band 19 is disposed between and partially encompasses the members 17 and 18 in a generally S- shaped fashion that forms with members 17 and 18 a movable cluster 14 permitting rolling motion between the rotatable members and the band 19 and also between the members and the guideway walls 12 and 13. a

The configuration of the band, as shown in FIG. 2a, is seen to have a diamond shaped cut out 22 that can be considered as being formed by a pair of triangular cut outs with apices 23 located at the opposite ends of the band and with bases that merge at a central location indicated at 24. This provides a built-in biasing force in the cluster 14 and which in the absence of other biasing forces orients the cluster at a null or referenced position which is generally intermediate the opposite ends 15 and 16 of the guideway l 1 as seen in the drawings.

The band 19 may be made of various materials that are known in the art but in the illustration are made of material that is electrically conductive such as stainless steel. In this respect, the bottom wall 13 has a plate-like resistive element 25 and the cluster is in electrical rolling contact with the element throughout its range of movement in the guideway 11. One of the fasteners 20, namely fastener 26, is connected, through a DC power source 27, to one side of a DC motor 28 by lead 29, and

the other side of the motor is connected by lead 30 to a fastener 31 in electrical contact with element 25 as seen in the drawings.

Walls 12 and 13 are rigidly spaced apart at the opposite ends 15 and 16 of the guideway 11 by means of blocks 32 and 33 respectively. Here at the opposite ends 15 and 16 of guideway 11, the device 10 is equipped with a pair of electromagnets 34 and 35 that include respective coils 40 and cores 41. Although both rollers 17 and 18 may be magnetically polarized, in the illustrated embodiment, roller 17 is made of permanently magnetizable material, such as steel, nickel or other suitable material, and is magnetically polarized to provide north and south poles at the opposite ends of the element as indicated in FIG. 2.

During use of the device 10 electromagnets 34 and 35 are so polarized, as indicated in FIG. 2, as to provide respective flux fields that repel element 17 and thus exert respectively opposing biasing forces on the cluster 14.

The advantages to the arrangement are best seen by reference to FIG. 3 and wherein the cluster 14 is shown at its null position attributed to the built-in biasing force exerted by band 19. Electromagnet 34 in this instance is connected in a circuit that includes a rheostat 45 and a DC power source 44 which is oriented in the circuit to polarize the electromagnet 34 in a manner such as to exert a repelling magnetic force on the cluster that would tend to urge the cluster in the direction of arrow 43. Electromagnet 35 on the other hand is connected in a circuit that includes a Bourdon tube 46 in electrical contact with a resistive element 47 connected in series with a DC power source 48 that is suitably oriented to polarize the electromagnet 35 in a manner such as to also exert a repelling magnetic force on the rotatable element 17 of cluster 14 but in the direction of arrow 42. The Bourdon tube 45 in this instance is arranged to sense the pressure in the outlet pipe 49 of a fluid pump 50 that is driven by DC motor 28. In the arrangement depicted in FIG. 3, rheostat 45 is so adjusted as to provide a current flow in the coils of electromagnet 34 that will setup a magnetic flux field repelling the cluster 14 with a biasing force that is equivalent to the counterbias exerted on the cluster by the field of electromagnet 35 under the pressure condition being developed in the outlet pipe 49 of pump 50. Under such circumstances, the current flow to motor 28 is determined by the resistant of element 25 between the fastener 31 and the point 51 of contact with the low resistance band portion 21 of cluster 14. If the pressure in the outlet pipe 49 increases for reasons, for example, of an increase in the intake pressure, tube 46 will tend to straighten out and by wiping resistive element 47 reduce the resistance in the circuit including electromagnet 35. This will increase the current flow in the coils of electromagnet 35 and in turn will increase the repelling force on the cluster 14 exerted by electromagnet 35 and tend to urge the cluster in the direction of arrow 42 against the repelling force exerted by the flux field of electromagnet 34 and against the built-in biasing force attributed to the band structure. Movement in the direction of arrow 42 of the cluster 14, will, of course, cause an increase in resistance in the motor circuit and a corresponding decrease in motor torque and resultant outlet pressure.

By adjusting rheostat 45 so that there is a higher current flow in electromagnet 34, cluster 14 can be moved in the direction of arrow 43 against the biasing force attributed to the band by movement beyond the null position in this direction and against the counterbiasing force attributable to electromagnet 35. As the cluster moves in this direction, the resistance in the motor circuit will decrease and a resulting higher pressure will be developed in the outlet pipe 49. The circuit involving the Bourdon tube 46 will accordingly, adjust itself to the increase in pressure and generate a cluster repelling field of greater magnitude to stabilize the cluster at an equilibrium position which is offset from the null position provided by the band structure. Consequently, by simply varying the rheostat 45 in the illustrated embodiment one can vary the reference position for the cluster and thus regulate the pump in response to pressures that deviate from that which would be determined by the built-in mechanical biasing forces of the device.

While having regard to the detailed description given in the consideration of the embodiment shown in FIGS. 1 through 3 inclusive, reference is next made to the embodiment shown in FIGS. 4 through 8 inclusive. In this instance, the roller-band device is designated at 55 and includes a guideway 56 that is provided in the spaced apart and parallel guidewalls 57 and 58. The band means 59 in this embodiment includes a pair of thin flexible rectangular components 60 and 61 that are spaced apart and fastened in parallel to diagonally opposite ends of walls 57 and 58 by means of fasteners 62 and 63 respectively. Both of the rollers 64 and 65 are right cylindrical elements with diameters that in summation exceed the distance between walls 57 and 58.

' The band components 60 and 61 entwine the rollers 64 and 65 in an S-shaped parallel fashion that provides a free rolling cluster which is unbiased by any mechanical means attributable to the band structure or arrangement of the wall. The guideway 56 as seen in FIG. 4 is mounted upright so that under the influence of gravity, the rollers 64 and 65, and hence also the cluster 70, are urged to the lower end 71 of the guideway. I-Iere device 55 has a U-shaped permanent magnet 72 that between its opposite legs 74 supports an incandescent lamp 73 which is connected to a suitable power source. The walls 57 and 58 are spaced apart at the lower and upper ends, 71 and 75 of the guideway 56, by suitable blocks 76. The guideway structure is made from suitable electrical insulating material such as a suitable plastic, and the front wall 58 is secured to the blocks 76 by means of fasteners 77. The front wall 58 has a transparent section 66 so that the position of the cluster 70 along the guideway can be read by referencing the position of the illuminated cluster to a scale 78 printed on the face of the wall 58.

Rollers 64 and 65 are maintained with their rotation axes in parallel by the band components and are right cylindrical elements in the embodiment illustrated. Roller 64 may be made of nonmagnetic material such as a suitable acrylic plastic but roller 65 in the embodiment is so constructed as to provide a means which can be magnetically polarized by the passage of current through the band components 60 and 61. In this respect, roller 65 as seen in FIG. 7 and 8 is in the form of a right cylindrical element that has a pair of coaxially arranged hollow cylindrical end components 79 and 80. These components 79 and 80 are made of suitable electrically conductive material and are insulated from each other in the roller structure by means of an annular insulation section 81 which is interposed between the components and fixed to the components intermediate the opposite ends 82 and 83 of the roller 65. Roller 65 has an axially extending core piece 84 that extends through the hollows of the components 79 and 80 and which is insulated from the components 79 and 80 at its opposite ends by suitable annular insulation elements designated at 85. The hollow 86 of the roller 65 has a coil 87 formed by a suitable wire having surface insulation and which is electrically connected at its opposite ends 88 and 89 to the respective electrically conductive components 79 and 80 of the assembled roller 65.

In the assembled roller-band device 55 the respective components 79 and 80 of roller 65 are in rolling electrical contact with the respective components 60 and 61 of the band structure 59 so that when the terminals of a suitable DC power source are connected to the respective band components 60 and 61, coil 87 is electrically energized by connection with the source and serves as an electromagnetic means that is magnetically polarized.

In the embodiment illustrated in FIGS. 4 through 8, band component 61 is connected by fasteners 63 to a lead 90 that is in turn connected to one of the output terminals 91 of a DC generator 92 while the other band component 60 is connected to the other output terminal 93 by a lead 94 electrically connected to fasteners 62 and having a variable resistor 95 and a suitable DC power source 96 connected in series.

In the embodiment illustrated in FIGS. 4 through 8, the device 55 is used to provide a visual readout of the rpm for the drive shaft 97 for generator 92. The variable resistor 95 of DC power source 96 are provided in ,the circuit to initially polarize the electromagnetic roller 65 and to develop a field strength causing repulsion of the cluster 70 from magnet 72 with a force sufficient to overcome gravity forces applied to the .cluster and move the cluster vertically to a position at which the degenerized state of generator 92 can be visually referenced against the markings of scale 78. Thus, by adjusting the variable resistor one can adjust the position of the cluster 70 along the guideway to a suitable reference position for calibration purposes. Generator 92 is arranged in the circuit to develop a DC current which is additive to that of the power source 96 and in response to rotation of shaft 97 generates a current that increases the field strength of the magnetically polarized roller element 65 and thus causes the cluster 70 to assume an elevated position indicative of the rpm of shaft 97 and which can be read by reference to the calibrated marking of scale 78.

Reference is now made to the embodiment of the invention shown in FIGS. 9 through 11 inclusive and wherein the roller-band device is generally designated at 100. The device 100, in this instance, has a guideway 101 that includes opposite guidewalls 102 and 103. Walls 102 and 103 are equally spaced apart throughout the range of movement of the roller-band cluster 104 and are supported at the opposite ends 105 and 106 of the guideway by end blocks 107.

The band means 108 of device 100 includes a pair of spaced fin rectangular electrically conductive band components 109 and 110 as in the last described embodiment and which are secured under tension to diametrically opposite ends of walls 102 and 103 by fasteners designated at 11 1 and 112.

The rotatable members or rollers 113 and 114 of the device are right cylindrical elements in the embodiment and with the wall spacing and band arrangement, this provides a free rolling cluster 104 that is unbiased by any built-in mechanical biasing means. Roller 114, like roller 64 in the previous embodiment is made of electrically nonconductive material such as a suitable plastic material. While roller 113 is identical instructure to the roller 65 described in the previous embodiment, roller 113 accordingly, can be magnetically polarized by connecting the band components 109 and 110 to the output terminals of a suitable DC source to provide a magnetically polarized component in the cluster and which will facilitate movement and orientation of the cluster in the guideway by means developing a magnetic field that will repel the element 113. In the embodiment illustrated the coil of roller '113 is energized by connecting the band components 109 and 1 10 in series with a variable resistor 115 and a suitable DC power source 116 and which are electrically interconnected in series by a lead 117 connected at its opposite ends to fasteners 111 and 112 in the top wall 102 of guideway 101.

Roller-band device 111 is also equipped with a pair of electromagnets 118 and 119 which are suitably secured at the opposite ends 105 and 106 respectively of guideway 101. These electromagnets 118 and 119 are identical in structure to those described in the first embodiment and during use of the device 100 are polarized, as indicated in FIG. 10, to provide magnetic flux fields that repel the cluster 104 and accordingly, provide oppositely directed forces that tend to bias the cluster in opposite directions.

As best seen in FlG. 11, the coil of electromagnet 119 is connected in series with a variable resistor 121 and a DC power source 120 that is oriented in the circuit to polarize the electromagnet 119 in a manner such as to magnetically repel roller element 113. It is deemed obvious that the strength of the field can be varied by suitably controlling the variable resistor 121 to vary the current delivered to the coils of the electromagnet 119.

The roller-band device 100 in this embodiment, as seen in FIG. 11, is connected to a fluid circuit that includes a pump 122 driven by a DC motor 123 and having an outlet pipe 124 which contains an electrical heating element 125 that is connected to a suitable AC power source 126. The device 100 is used to control speed of the motor 123 in response to temperature changes downstream from heating element 125 and in this respect, the coil of electromagnet 1 18 is connected to the output terminal of a suitable temperature sensing device 127 having a DC output which increases and decreases with respective rises and falls in the temperature of the fluid. Sensor 127 is connected to the coils in a manner such as to polarize the magnet 118 and develop a magnetic field which will repel element 113.

The bottom wall 103 of guideway 101 is equipped with an elongated plate-like resistive element 128 that underlies band component 110 and this element 128 is electrically connected by fastener 129 and lead 130 to one terminal of DC motor 123. Band component 110 is in rolling contact with the resistive element 128 and is electrically connected through fastener 112 in bottom wall 103 and electrical lead 131 to the other input terminal of motor 123. Lead 131 contains a variable resistor 132 and a DC power source 133 in series as seen in FIG. 11.'

In the operation of the device variable resistors 121 and 132 are manually controlled to provide the desired temperature-condition at sensor 127 and to provide a suitable intermediate position in the guideway for cluster 104. Thereafter, if the temperature rises downstream from heating element 125, current flow to the coil of electromagnet 118 increases and this results in an increase field strength causing repulsion of the cluster in the direction of arrow 134. This in turn decreases the resistance in the motor circuit attributable to resistive element 128 and causes a speedup of the motor 123 and an increase in the output flow rate so that the rise in fluid temperature caused by heating element 125 is diminished. On the other hand, if the temperat'ure conditions downstream of element 125 should fall, as for example due to an increase in fluid inlet pressure, then the current delivered to the coil of electromagnet 118 is decreased. This results in a decreased field strength that permits the cluster 104 to move in the direction of arrow 135 under the influence of the field of coil 119 so that the cluster than assumes a position determined by the opposing biasing forces attributed to the fields developed by electromagnets 1 18 and 119. As cluster 104 moves in the direction of arrow 135 the resistance in the motor circuit of course, increases and this results in a decreased flow rate in the output pipe 124 and permits attainment of a higher fluid temperature through contact with element 125.

In the current embodiment, roller element 113 is shown in the form of an electromagnet which is energized by an exterior power source, will readily occur to those skilled in the art that a roller element in the form of a permanent magnet which is properly oriented to be repelled by the fields of electromagnets 118 and 119 may be used in lieu of the formed used in the embodiment.

While only certain preferred embodiments of this inverition have been shown and described by way of illustration, many modifications will occur to those skilled in the art and it is, therefore, desired that it be understood that it is intended herein to cover all such modifications as fall within the true spirit and scope of this invention.

What is claimed as new and what it is desired to secure by Letters Patent of the United States is:

1. In a roller-band device comprising a pair of rotatable members that have axes of rotation, a guideway having opposite ends and spaced apart walls which supmovable cluster with the members and permits rolling I motion between said members and said band means and between said members and said walls, the improvement where at least one of said members comprises first magnetically polarized means, where the device further comprises second magnetically polarized means located at one of said ends and oriented to exert a repelling magnetic force on said first magnetically polarized means.

2. The improvement in accord with claim 1 where said first magnetically polarized means is a permanent magnet.

3. The improvement in accord with claim 1 where said second magnetically polarized means is a permanent magnet.

4. The improvement in accord with claim 1 where said first magnetically polarized means is an electromagnetic means,

5. The improvement in accord with claim 1 where said second magnetically polarized means is an electromagnetic means.

6. The improvement in accord with claim 1 where said first magnetically polarized means is a permanent magnet, and said second magnetically polarized means is an electromagnetic means.

7. The improvements in accord with claim 1 where said first magnetically polarized means is an electromagnetic means, and said second magnetically polarized means is a permanent magnet.

8. The improvement in accord with claim 1 where said device further comprises third magnetically polarized means located at the other of said ends and oriented to exert a repelling magnetic force on said first magnetically polarized means.

9. The improvement in accord with claim 8 where said first magnetically polarized means is a permanent magnet.

10. The improvement in accord with claim 8 where said first magnetically polarized means is an electromagnetic means.

11. The improvement in accord with claim 8 where said second magnetically polarized means is an electromagnetic means.

12. The improvement in accord with claim 8 where said first magnetically polarized means is a permanent magnet and said second magnetically polarized means is an electromagnetic means.

13. The improvement in accord with claim 8 where said first magnetically polarized means is a permanent magnet, said second magnetically polarized means is an electromagnetic means, and said third magnetically polarized means is an electromagnetic means.

14. The improvement in accord with claim 8 where said first magnetically polarized means is an electromagnetic means, said second magnetically polarized means is an electromagnetic means, and said third magnetically polarized means is an electromagnetic means.

15. In a roller-band device comprising a pair of rotatable members that have axes of rotation, a guideway having opposite ends and spaced apart walls which support, guide and restrain said members and are spaced apart a distance less than the sum of the diameters of said members, and flexible band means supported under tension between said walls and maintaining said axes in parallel, said band means having a portion disposed between and partially encompassing rolling motion between said members and said band means and between said members and said walls, the improvement where said band means includes spaced electrically conductive components respectively electrically connected to the opposite terminals of a DC electrical power source, where at least one of said members comprises first magnetically polarized means that includes an electrically conductive coil having opposite ends electrically connected to said electrically conductive components, and where the device further comprises second magnetically polarized means located at one of the opposite guideway ends and oriented to exert a repelling magnetic force on said first magnetically polarized means.

16. The improvement in accord with claim where said first magnetically polarized means further includes spaced electrically conductive components electrically connected to the opposite coil ends respectively and arranged in rolling electrical contact with the respective components of said band means.

17. The improvement in accord with claim 15 where said second magnetically polarized means is a permanent magnet.

18. The improvement in accord with claim 15 where said second magnetically polarized means is an electromagnetic means electrically connected to a DC electrical power source.

19. The improvement in accord with claim 15 where the device further comprises third magnetically polarized means located at the other of the guideway ends to exert a repelling magnetic force on said first magnetically polarized means.

20. The improvement in accord with claim 19 where said first magnetically polarized means further includes spaced electrically conductive components electrically connected to the opposite coil ends respectively and arranged in rolling electrical contact with the respective components of said band means, and where said second magnetically polarized means is an electromagnetic means electrically connected to a DC power source. and where said third magnetically polarized means is an electromagnetic means electrically connected to a DC power source. 

1. In a roller-band device comprising a pair of rotatable members that have axes of rotation, a guideway having opposite ends and spaced apart walls which support, guide and restrain said members and are spaced apart a distance less than the sum of the diameters of said members, and flexible band means supported under tension between said walls and maintaining said axes in parallel, said band means having a portion disposed between and partially encompassing said members in a generally S-shaped fashion that forms a movable cluster with the members and permits rolling motion between said members and said band means and between said members and said walls, the improvement where at least one of said members comprises first magnetically polarized means, where the device further comprises second magnetically polarized means located at one of said ends and oriented to exert a repelling magnetic force on said first magnetically polarized means.
 2. The improvement in accord with claim 1 where said first magnetically polarized means is a permanent magnet.
 3. The improvement in accord with claim 1 where said second magnetically polarized means is a permanent magnet.
 4. The improvement in accord with claim 1 where said first magnetically polarized means is an electromagnetic means.
 5. The improvement in accord with claim 1 where said second magnetically polarized means is an electromagnetic means.
 6. The improvement in accord with claim 1 where said first magnetically polarized means is a permanent magnet, and said second magnetically polarized means is an electromagnetic means.
 7. The improvements in accord with claim 1 where said first magnetically polarized means is an electromagnetic means, and said second magnetically polarized means is a permanent magnet.
 8. The improvement in accord with claim 1 where said device further comprises third magnetically polarized means located at the other of said ends and oriented to exert a repelling magnetic force on said first magnetically polarized means.
 9. The improvement in accord with claim 8 where said first magnetically polarized means is a permanent magnet.
 10. The improvement in accord with claim 8 where said first magnetically polarized means is an electromagnetic means.
 11. The improvement in accord with claim 8 where said second magnetically polarized means is an electromagnetic means.
 12. The improvement in accord with claim 8 where said first magnetically polarized means is a permanent magnet and said second magnetically polarized means is an electromagnetic means.
 13. The improvement in accord with claim 8 where said first magnetically polarized means is a permanent magnet, said second magnetically polarized means is an electromagnetic means, and said third magnetically polarized means is an electromagnetic means.
 14. The improvement in accord with claim 8 where said first magnetically polarized means is an electromagnetic means, said second magnetically polarized means is an electromagnetic means, and said third magnetically polarized means is an electromagnetic means.
 15. In a roller-band device comprising a pair of rotatable members that have axes of rotation, a guideway having opposite ends and spaced apart walls which support, guide and restrain said members and are spaced apart a distance less than the sum of the diameters of said members, and flexible band means supported under tension between said walls and maintaining said axes in parallel, said band means having a portion disposed between and partially encompassing said members in a generally S-shaped fashion that forms a movable cluster with the members and permits rolling motion between said members and said band means and between said members and said walls, the improvement where said band means includes spaced electrically conductive components respectively electrically connected to the opposite terminals of a DC electrical power source, where at least one of said members comprises first magnetically polarized means that includes an electrically conductive coil having opposite ends electrically connected to said electrically conductive components, and where the device further comprises second magnetically polarized means located at one of the opposite guideway ends and oriented to exert a repelling magnetic force on said first magnetically polarized means.
 16. The improvement in accord with claim 15 where said first magnetically polarized means further includes spaced electrically conductive components electrically connected to the opposite coil ends respectively and arranged in rolling electrical contact with the respective components of said bAnd means.
 17. The improvement in accord with claim 15 where said second magnetically polarized means is a permanent magnet.
 18. The improvement in accord with claim 15 where said second magnetically polarized means is an electromagnetic means electrically connected to a DC electrical power source.
 19. The improvement in accord with claim 15 where the device further comprises third magnetically polarized means located at the other of the guideway ends to exert a repelling magnetic force on said first magnetically polarized means.
 20. The improvement in accord with claim 19 where said first magnetically polarized means further includes spaced electrically conductive components electrically connected to the opposite coil ends respectively and arranged in rolling electrical contact with the respective components of said band means, and where said second magnetically polarized means is an electromagnetic means electrically connected to a DC power source, and where said third magnetically polarized means is an electromagnetic means electrically connected to a DC power source. 